On 06/12/2018 18:39, Souptick Joarder wrote:
Previouly drivers have their own way of mapping range of
kernel pages/memory into user vma and this was done by
invoking vm_insert_page() within a loop.
As this pattern is common across different drivers, it can
be generalized by creating a new function and use it across
the drivers.
vm_insert_range is the new API which will be used to map a
range of kernel memory/pages to user vma.
This API is tested by Heiko for Rockchip drm driver, on rk3188,
rk3288, rk3328 and rk3399 with graphics.
Signed-off-by: Souptick Joarder <jrdr.linux@xxxxxxxxx>
Reviewed-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Reviewed-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Tested-by: Heiko Stuebner <heiko@xxxxxxxxx>
---
include/linux/mm.h | 2 ++
mm/memory.c | 38 ++++++++++++++++++++++++++++++++++++++
mm/nommu.c | 7 +++++++
3 files changed, 47 insertions(+)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index fcf9cc9..2bc399f 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2506,6 +2506,8 @@ unsigned long change_prot_numa(struct vm_area_struct *vma,
int remap_pfn_range(struct vm_area_struct *, unsigned long addr,
unsigned long pfn, unsigned long size, pgprot_t);
int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *);
+int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
+ struct page **pages, unsigned long page_count);
vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
unsigned long pfn);
vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
diff --git a/mm/memory.c b/mm/memory.c
index 15c417e..84ea46c 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1478,6 +1478,44 @@ static int insert_page(struct vm_area_struct *vma, unsigned long addr,
}
/**
+ * vm_insert_range - insert range of kernel pages into user vma
+ * @vma: user vma to map to
+ * @addr: target user address of this page
+ * @pages: pointer to array of source kernel pages
+ * @page_count: number of pages need to insert into user vma
+ *
+ * This allows drivers to insert range of kernel pages they've allocated
+ * into a user vma. This is a generic function which drivers can use
+ * rather than using their own way of mapping range of kernel pages into
+ * user vma.
+ *
+ * If we fail to insert any page into the vma, the function will return
+ * immediately leaving any previously-inserted pages present. Callers
+ * from the mmap handler may immediately return the error as their caller
+ * will destroy the vma, removing any successfully-inserted pages. Other
+ * callers should make their own arrangements for calling unmap_region().
+ *
+ * Context: Process context. Called by mmap handlers.
+ * Return: 0 on success and error code otherwise
+ */
+int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
+ struct page **pages, unsigned long page_count)
+{
+ unsigned long uaddr = addr;
+ int ret = 0, i;
Some of the sites being replaced were effectively ensuring that vma and
pages were mutually compatible as an initial condition - would it be
worth adding something here for robustness, e.g.:
+ if (page_count != vma_pages(vma))
+ return -ENXIO;
?
(then you could also clean up a couple more places where you're not
already removing such checks)
Robin.
+
+ for (i = 0; i < page_count; i++) {
+ ret = vm_insert_page(vma, uaddr, pages[i]);
+ if (ret < 0)
+ return ret;
+ uaddr += PAGE_SIZE;
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL(vm_insert_range);
+
+/**
* vm_insert_page - insert single page into user vma
* @vma: user vma to map to
* @addr: target user address of this page
diff --git a/mm/nommu.c b/mm/nommu.c
index 749276b..d6ef5c7 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -473,6 +473,13 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
}
EXPORT_SYMBOL(vm_insert_page);
+int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
+ struct page **pages, unsigned long page_count)
+{
+ return -EINVAL;
+}
+EXPORT_SYMBOL(vm_insert_range);
+
/*
* sys_brk() for the most part doesn't need the global kernel
* lock, except when an application is doing something nasty
